Angiographic predictors of reocclusion after thrombolysis: results from the Thrombolysis in Myocardial Infarction (TIMI) 4 trial

"Incidence and Clinico-Radiological Correlations of Early Arterial Reocclusion After Successful Thrombectomy in Acute Ischemic Stroke"

About half of acute stroke patients treated with mechanical thrombectomy (MT) do not show clinical improvement despite successful recanalization. Early arterial reocclusion (EAR) may be one of the causes that explain this phenomenon. We aimed to analyze the incidence and clinico-radiological correlations of EAR after successful MT. A consecutive series of patients treated with MT between 2010 and 2018 at a single-center included in a prospective registry was retrospectively reviewed. Specific inclusion criteria for the analysis were (1) successful recanalization after MT and (2) availability of pretreatment CT perfusion and follow-up MRI. EAR was evaluated in the follow-up MR angiography. Adjusted regression models were used to analyze the association of EAR with pretreatment variables, infarct growth, final infarct volume, and clinical outcome at 90 days (ordinal distribution of the modified Rankin Scale scores). Out of 831 MT performed, 218 (26%) patients fulfilled inclusion criteria, from whom 13 (6%) suffered EAR. In multivariate analysis controlled by confounders, EAR was independently associated with poor clinical outcome (aOR = 3.2, 95%CI = 1.16-9.72, p = 0.039), greater final infarct volume (aOR = 3.8, 95%CI = 1.93-7.49, p < 0.001), and increased infarct growth (aOR = 8.5, CI95% = 2.04-34.70, p = 0.003). According to mediation analyses, the association between EAR and poor clinical outcome was mainly explained through its effects on final infarct volume and infarct growth. Additionally, EAR was associated with non-cardioembolic etiology (adjusted Odds Ratio (aOR) = 10.1, 95%CI = 1.25-81.35, p = 0.030) and longer procedural time (aOR = 2.6, 95%CI = 1.31-5.40, p = 0.007). Although uncommon, EAR hampers the benefits of successful recanalization after MT resulting in increased infarct growth and larger final lesions.

Instant reocclusion following mechanical thrombectomy of in situ thromboocclusion and the role of low-dose intra-arterial tirofiban

BACKGROUND

An in situ thromboocclusion (IST) is defined as an infarct extensively involving all or most of a stenosed arterial territory, which is one major stroke mechanism related to intracranial atherosclerosis (ICAS). We focused on ISTs occurring in major cerebral arteries and analyzed their rate of instant reocclusion during mechanical thrombectomy (MT) compared with non-ISTs. Also, we introduced a treatment strategy of low-dose intra-arterial tirofiban administration to prevent such reocclusion following repeat recanalization, and evaluated its safety and efficacy.

METHODS

We analyzed 168 consecutive patients treated with MT over a 2-year period from May 2011 to April 2013. During MT, if angiography following a successful recanalization showed stenosis at the occlusion site, we performed additional angiographic runs every 10 min for 30 min after the recanalization. Then, if angiography revealed reocclusion, we performed a repeat recanalization, using the same MT technique but additionally followed by low-dose intra-arterial tirofiban infusion. Time-of-flight MR angiography or CT angiography was performed to confirm any underlying ICAS at the occlusion site 5-7 days after the procedure. The patients who had confirmed underlying ICAS were included in the IST cohort.

RESULTS

Of 168 enrolled patients, we excluded 36 who could not be checked for underlying ICAS at the occlusion site for one of the following reasons: recanalization failure (n = 11), rescue stenting after tirofiban failure (n = 5) and lack of follow-up vascular imaging (n = 20). The incidence of IST was 30.3% (40/132). All IST patients were confirmed to have underlying ICAS by follow-up vascular imaging. Instant reocclusion after successful recanalization was significantly more frequent in the IST cohort [26/40 (65%) vs. 3/92 (3.3%); p < 0.001]. Regarding the efficacy of low-dose intra-arterial tirofiban infusion, 85.7% of the reocclusion patients finally achieved a thrombolysis in cerebral infarction score 2/3 recanalization, but in the remaining 14.3% of the cases, the condition was refractory to the procedure and required rescue stenting. There were no cases of symptomatic intracranial hemorrhage following the procedure.

CONCLUSIONS

In situ thromboocclusion was characterized by a significantly higher chance of instant reocclusion during MT. In such cases, low-dose intra-arterial tirofiban administration may be effective and safe. However, future confirmation by prospective multicenter trials seems necessary.

Reperfusion therapy for STEMI: is there still a role for thrombolysis in the era of primary percutaneous coronary intervention?

In the past ten years, primary percutaneous coronary intervention (PCI) has replaced thrombolysis as the revascularisation strategy for many patients presenting with ST-segment elevation myocardial infarction (STEMI). However, delivery of primary PCI within evidence-based timeframes is challenging, and health-care provision varies substantially worldwide. Consequently, even with the ideal circumstances of rapid initial diagnosis, long transfer delays to the catheter laboratory can occur. These delays are detrimental to outcomes for patients and can be exaggerated by variations in timing of patients' presentation and diagnosis. In this Series paper we summarise the value of immediate out-of-hospital thrombolysis for STEMI, and reconsider the potential therapeutic interface with a contemporary service for primary PCI. We review recent trial data, and explore opportunities for optimisation of STEMI outcomes with a pharmacoinvasive approach.

Optimizing the use of thrombolytics in ST-segment elevation myocardial infarction

The advent of thrombolytic therapy was a major advance in the treatment of ST-segment elevation myocardial infarction (STEMI). The administration of fibrinolytic reperfusion therapy can reduce mortality rates by as much as 30%, with the greatest benefit observed if therapy is administered soon after symptom onset. Outcomes with thrombolytic therapy are improved if there is adjunctive treatment with aspirin, clopidogrel and an anti-thrombin agent. Although there is evidence that primary percutaneous coronary intervention (PCI) is the most effective reperfusion strategy, the majority of hospitals still do not have PCI capabilities and, thus, thrombolytic therapy remains a cornerstone of treatment for STEMI. Trials of thrombolytic therapy have demonstrated that initial patency rates can approach 85%, but there is still a need for improvement of non-invasive markers that predict failure or re-occlusion of the infarct-related artery. Because of the overwhelming data demonstrating the importance of rapid reperfusion, current studies are examining the role of earlier treatment of patients with STEMI via pre-hospital administration and/or coordinated systems for rapid diagnosis, transfer and delivery of definitive care. Facilitated PCI, a strategy of thrombolytic therapy followed by immediate PCI, has not been shown to be beneficial and current studies are examining the optimal timing of coronary angiography after thrombolytic therapy.

Sustained coronary patency after fibrinolytic therapy as independent predictor of 10-year cardiac survival Observations from the Antithrombotics in the Prevention of Reocclusion in COronary Thrombolysis (APRICOT) trial

BACKGROUND

Whether late coronary patency after myocardial infarction has prognostic impact independent of left ventricular function remains a matter of debate. Reocclusion rates in the first year after fibrinolysis vary between 20% and 30%. Of all reocclusions, about 30% present as clinical reinfarction, associated with a 2-fold-increased risk of mortality. The clinical impact of reocclusion that presents without reinfarction has not been studied; but an association has been demonstrated with impaired contractile recovery of left ventricular function, the strongest prognosticator of long-term outcome. We therefore studied the impact of 3-month coronary patency after successful fibrinolysis on 10-year cardiac survival.

METHODS

In the APRICOT-1 trial, 248 ST-elevation myocardial infarction patients with an open infarct artery 24 hours after fibrinolysis had 3-month repeated angiography. Ten-year clinical follow-up was complete in 99.6%.

RESULTS

The reocclusion rate was 29% (71/248). Of these reocclusions, 24% presented as clinical reinfarction (17/71). Cardiac survival at 10 years was 73% in patients with a reoccluded infarct artery and 88% in patients with sustained patency (P < .01). This difference was also present in patients in whom reocclusion was only detected as a result of systematic repeated angiography, that is, in the absence of reinfarction or ischemic symptoms between angiograms (70% vs 86%, P < .03). Multivariable analysis identified sustained patency at 3-month angiography as independent predictor of 10-year cardiac survival (hazard ratio 2.10, 95% CI 1.10-4.02) together with left ventricular ejection fraction.

CONCLUSIONS

Sustained infarct artery patency in the first 3 months after successful fibrinolysis is a strong predictor of 10-year cardiac survival, independent of left ventricular function. Notably, this also holds true when reocclusion occurs without signs of clinical reinfarction or recurrent ischemia. Therefore, future preventive strategies should also focus on "clinically silent" reocclusions. Additional studies on better antithrombotic regimens and the combination with a routine invasive strategy early after successful fibrinolysis are warranted.

Relationship between infarct artery location, epicardial flow, and myocardial perfusion after primary percutaneous revascularization in acute myocardial infarction

BACKGROUND

The association between infarct artery location, reperfusion success, and clinical outcomes after primary percutaneous coronary intervention (PCI) has not been characterized. We examined the infarct artery-specific impact of epicardial and myocardial flow and reperfusion after primary PCI for acute myocardial infarction.

METHODS

Among 2082 patients undergoing primary PCI in the CADILLAC trial, myocardial blush grade, TIMI flow grade, ST-segment resolution, and clinical outcomes were analyzed according to the infarct artery.

RESULTS

Baseline clinical characteristics did not significantly differ between patients experiencing infarction in the left anterior descending (LAD, 37%) versus left circumflex (18%) and right coronary artery (46%) distributions. Baseline left ventricular function was reduced, and collateral flow was less commonly present in patients with infarction involving the LAD. Achievement of final TIMI-3 flow, grade 3 myocardial blush, and ST-segment resolution >70% was also significantly less common in anterior infarction. Patients with anterior versus nonanterior infarction had significantly higher mortality at 30 days (3.4% vs 1.3%, P = .0006) and 1 year (6.5% vs 2.9%, P < .0001) and had increased 1-year rates of reinfarction (3.6% vs 1.7%, P = .009) and ischemic target vessel revascularization (16.1% vs 11.7%, P = .006). By multivariate analysis, LAD infarction was a powerful independent predictor of 1-year mortality (odds ratio 2.45, P = .009).

CONCLUSIONS

Acute myocardial infarction involving the LAD distribution is associated with reduced left ventricular function, less frequent collateral flow, impaired myocardial perfusion and decreased reperfusion success, findings associated with reduced survival, and increased major adverse cardiac events compared with other vascular territories. These data provide mechanistic insights to the adverse prognosis of patients with anterior infarction.

Clinical contribution of the collateral circulation to myocardial protection

This section describes the clinical evidence for benefit from coronary collateral channels. There is data to suggest the presence of a protective effect in patients sustaining myocardial infarction regardless of whether they receive reperfusion therapy, and whether the collaterals were preformed. The role of pre-infarction angina in stimulating collateral development remains a contentious issue.

High-grade infarct-related stenosis after successful thrombolysis: strong predictor of reocclusion, but not of clinical reinfarction

BACKGROUND

After successful thrombolysis, a high-grade stenosis at 24-hour angiography is strongly predictive of reocclusion and is often believed to result in high reinfarction rates. However, routine angioplasty did not reduce death or reinfarction in past trials. Systematic angiographic follow-up shows that reocclusion often occurs without clinical reinfarction. This study investigates whether the increased risk for reocclusion associated with a high-grade lesion translates into impaired clinical outcome.

METHODS

In the ischemia-guided Antithrombotics in the Prevention of Reocclusion in COronary Thrombolysis (APRICOT-1) trial, 240 patients with ST-elevation MI who had an open infarct artery 24 hours after thrombolysis had 3-month repeat angiography to assess reocclusion, with clinical follow-up at 3 months and 3 years.

RESULTS

On the basis of the optimal discriminative stenosis severity, the reocclusion rate was 40% (47/118) in patients with a high-grade residual stenosis and 16% (20/122) in patients with a low-medium-grade lesion (risk ratio [RR], 2.43; 95% CI, 1.54-3.84; P <.01). Three-month death and reinfarction rates did not differ: 6% (7/118) versus 9% (11/122; RR, 0.66; 95% CI, 0.26-1.64; P = not significant). Systematic angiographic follow-up revealed that reocclusion of a high-grade lesion occurred in the absence of clinical reinfarction in 85% (40/47) of patients, as compared with 45% (9/20) in patients with a low-medium-grade stenosis (RR, 1.89; 95% CI, 1.15-3.12; P <.01). Despite an independent association with reocclusion, a high-grade stenosis was not predictive of either short- or long-term death and reinfarction.

CONCLUSIONS

After successful thrombolysis and adopting an ischemia-guided revascularization strategy, patients with a high-grade stenosis experience death/reinfarction rates similar to that of patients with a low-medium-grade lesion. This is true despite a 2- to 3-fold higher risk for reocclusion. The finding that reocclusion of a high-grade lesion often occurs without clinical reinfarction explains the absence of a relationship between a severe stenosis and death/reinfarction. Appreciation of these observations may contribute to an optimal design of a future randomized trial to re-evaluate the impact of a routine invasive strategy.

Association of a pulsatile blood flow pattern on coronary arteriography and short-term clinical outcomes in acute myocardial infarction

OBJECTIVES

We hypothesized that recognition of systolic flow reversal (pulsatile flow) after thrombolytic administration on coronary angiography is associated with angiographic and electrocardiogram findings reflecting impaired myocardial perfusion, as well as poorer clinical outcomes.

BACKGROUND

Reversal of systolic flow on Doppler velocity wire recordings has been associated with impaired tissue perfusion on myocardial contrast echocardiography in the setting of myocardial infarction (MI).

METHODS

Patients (n = 1,062) with a patent infarct-related artery were drawn from the Thrombolysis In Myocardial Infarction (TIMI) 10, TIMI 14, and Integrillin and Tenecteplase acute MI trials.

RESULTS

Pulsatile flow (systolic flow reversal with cessation of antegrade contrast-dye motion or frank reversal of contrast-dye motion during systole) at 60 min after fibrinolytic administration was present in 11.0% of patients. Pulsatile flow was associated with higher corrected TIMI frame counts (slower epicardial flow) (median 40.1 frames, IQ 30 of 63 vs. 30 frames, interquartile 22 of 42, p < 0.0001), a closed microvasculature (TIMI myocardial perfusion grades 0 of 1, 57.1% vs. 37.8%, p = 0.03) and less complete (> or =70%) ST-segment resolution (23.5% vs. 58.9%, p = 0.008). Patients with pulsatile flow had a higher risk of death or reinfarction at 30 days (10.3% vs. 5.0%, p = 0.019). After controlling for age, pulse, blood pressure, anterior MI location, epicardial flow, and creatine kinase, pulsatile flow remained associated with an increased risk of death/MI (odds ratio 3.1, p = 0.006).

CONCLUSIONS

A pulsatile pattern of flow is associated with impaired myocardial perfusion and poorer clinical outcomes independent of the velocity of antegrade flow in the epicardial artery. This simple and easily identifiable angiographic flow pattern may be useful in clinical risk stratification.

Early and long-term clinical outcomes associated with reinfarction following fibrinolytic administration in the Thrombolysis in Myocardial Infarction trials

OBJECTIVES

We hypothesized that early recurrent myocardial infarction (MI) following fibrinolytic administration would be assessed with higher mortality at both 30 days and 2 years.

BACKGROUND

Although early recurrent MI after fibrinolytic therapy has been associated with increased early mortality in the acute MI setting, its relation to long-term mortality has not been fully explored.

METHODS

Mortality data were ascertained in 20,101 patients enrolled in the Thrombolysis In Myocardial Infarction (TIMI) 4, 9, and 10B and Intravenous NPA for the Treatment of Infarcting Myocardium Early (InTIME-II) acute MI trials.

RESULTS

The frequency of symptomatic recurrent MI during the index hospitalization was 4.2% (836/20,101). Recurrent MI during the index hospital period was associated with increased 30-day mortality (16.4% [137/836] vs. 6.2% [1,188/19,260], p < 0.001). Likewise, recurrent MI was associated with a sustained increase in mortality up to two years, even after adjustments were made for covariates known to be associated with mortality and recurrent MI (hazard ratio 2.11, p < 0.001). However, this higher mortality at 2 years was due to an early divergence in mortality by 30 days and was not due to a significant increase in late mortality between 30 days and 2 years (4.38% [31/707] vs. 3.76% [685/18,206], p = NS). Percutaneous coronary intervention during the index hospitalization was associated with a lower rate of in-hospital recurrent MI (1.6% vs. 4.5%, p < 0.001) and lower two-year mortality (5.6% vs. 11.6%, p < 0.001). Performance of coronary artery bypass graft surgery was also associated with a lower recurrent rate of MI (0.7% vs. 4.3%, p < 0.001) and lower two-year mortality rate (7.95% vs. 10.6%, p = 0.0008).

CONCLUSIONS

Early recurrent MI is associated with increased mortality up to two years. However, most deaths occur early, and the risk of additional deaths between the index hospital period and two years was not significantly increased among patients with recurrent MI. Percutaneous coronary intervention during the index hospitalization was associated with a lower risk of recurrent MI and a lower risk of two-year mortality.

A randomized trial of transfer for primary angioplasty versus on-site thrombolysis in patients with high-risk myocardial infarction: the Air Primary Angioplasty in Myocardial Infarction study

OBJECTIVES

The Air Primary Angioplasty in Myocardial Infarction (PAMI) study was designed to determine the best reperfusion strategy for patients with high-risk acute myocardial infarction (AMI) at hospitals without percutaneous transluminal coronary angioplasty (PTCA) capability.

BACKGROUND

Previous studies have suggested that high-risk patients have better outcomes with primary PTCA than with thrombolytic therapy. It is unknown whether this advantage would be lost if the patient had to be transferred for PTCA, and reperfusion was delayed.

METHODS

Patients with high-risk AMI (age >70 years, anterior MI, Killip class II/III, heart rate >100 beats/min or systolic BP <100 mm Hg) who were eligible for thrombolytic therapy were randomized to either transfer for primary PTCA or on-site thrombolysis.

RESULTS

One hundred thirty-eight patients were randomized before the study ended (71 to transfer for PTCA and 67 to thrombolysis). The time from arrival to treatment was delayed in the transfer group (155 vs. 51 min, p < 0.0001), largely due to the initiation of transfer (43 min) and transport time (26 min). Patients randomized to transfer had a reduced hospital stay (6.1 +/- 4.3 vs. 7.5 +/- 4.3 days, p = 0.015) and less ischemia (12.7% vs. 31.8%, p = 0.007). At 30 days, a 38% reduction in major adverse cardiac events was observed for the transfer group; however, because of the inability to recruit the necessary sample size, this did not achieve statistical significance (8.4% vs. 13.6%, p = 0.331).

CONCLUSIONS

Patients with high-risk AMI at hospitals without a catheterization laboratory may have an improved outcome when transferred for primary PTCA versus on-site thrombolysis; however, this will require further study. The marked delay in the transfer process suggests a role for triaging patients directly to specialized heart-attack centers.

Safety of coronary stenting early after thrombolysis in patients with acute myocardial infarction: one- and six-month clinical and angiographic evolution

To determine the feasibility and safety of early posthrombolysis coronary stenting and the incidence of further reocclusion, we followed 99 consecutive patients with acute myocardial infarction thrombolyzed with rt-PA 2.0 +/- 0.8 hr after onset. Culprit artery was stented 14.0 +/- 7.0 hr after thrombolysis. All patients underwent clinical and angiographic follow-up at 1 and 6 months. Angiographic success was achieved in 99% of cases. Neither major cardiac events nor bleeding or vascular complications occurred during hospital stay. At 30 days, no events occurred and normal flow persisted in all stented arteries. At 6 months, only one artery reoccluded (1%), resulting in a nonfatal reinfarction. Restenosis rate was 21%. Contribution of the infarcted area to left ventricular function significantly increased from baseline to 30-day and to 6-month evaluations. Thus, early posthrombolysis stenting is a safe strategy with a low reocclusion rate, which seems to allow functional recovery of the infarcted area. Further studies are necessary to define its impact on survival and cost-effectiveness.

Keeping the coronary arteries open: current opportunities

Thrombolysis has reduced mortality from myocardial infarction, but effective opening of the artery with normal flow continues to be an important goal. Thrombolysis is not always as successful as it should be; alternatives include adjunctive therapy and mechanical opening of the arteries. In patients with acute coronary occlusion opening the artery should continue to be the primary aim.

Adaptive remodeling of the infarct-related artery is associated with recurrent ischemic events after thrombolysis in acute myocardial infarction

BACKGROUND

Recurrent ischemic events occur during the hospital stay of 7-32% of patients after successful thrombolytic treatment of acute myocardial infarction (AMI).

OBJECTIVE

To define the association between postinfarction angina pectoris and the clinical, angiographic, and intravascular ultrasound (IVUS) parameters of the infarct-related artery for consecutive prospectively included patients.

METHODS

Clinical, qualitative, and quantitative angiographic and IVUS data for 64 patients (56 men, aged 53+/-12 years) with thrombolysis of AMI were analyzed. All patients underwent coronary angiography and pre-interventional IVUS measurement electively within 1 month of AMI or at the time of the occurrence of postinfarction angina pectoris. Classification as adaptive or constrictive remodeling was according to whether the cross-sectional area of a vessel was larger or smaller than that of the proximal or distal reference segment.

RESULTS

Nineteen of the 64 patients (29.7%) suffered from recurrence of ischemic events (group 1), whereas 45 patients (60.3%, group 2) remained free from symptoms. In univariate analyses, multivessel disease (42 versus 24%, P= 0.0236) and adaptive remodeling (63 versus 24%, P= 0.0032) were found to occur more commonly among patients in group 1. The patients in group 1 exhibited larger total vessel cross-sectional areas than did the patients in group 2 (17.5+/-4.2 versus 14.9+/-6.1 mm2, P = 0.0556). In multivariate regression analysis, adaptive remodeling proved to be a significant predictor (P = 0.0145) of the recurrence of ischemic events after thrombolysis of AMI.

CONCLUSIONS

Adaptive remodeling of the infarct-related artery is associated with early postinfarction angina pectoris after thrombolysis of AMI.

Prognosis of patients with a recurrent acute myocardial infarction before and in the reperfusion era--a national study

BACKGROUND

Patients with recurrent acute myocardial infarction (AMI) are at increased risk for morbidity and mortality. We compared the outcome of patients with recurrent AMI hospitalized in coronary care units in the prereperfusion and reperfusion eras.

METHODS

The study population comprised 2 large-scale cohorts with recurrent AMI: (1) 1415 (24%) of 5839 consecutive patients with AMI hospitalized in 1981 to 1983 (Secondary Prevention Reinfarction Israeli Nifedipine Trial [SPRINT] Registry) and (2) 1093 (25%) of 4317 patients with AMI from three national surveys performed in 1992 to 1996.

RESULTS

Patients in the 1990s had significantly lower rates of heart failure and cardiogenic shock. The 7-day mortality declined from 18% in 1981-1983 to 10% in 1992-1996 (adjusted odds ratio [OR] 0.57 [0.44-0.75]), the 30-day mortality rate from 26% to 16% (OR 0.56 [0.44-0.71]), and the 1-year mortality rate from 39% to 26% (adjusted hazard ratio [HR] 0.64 [0.54-0.75]), respectively. In the 1992-1996 cohort, the adjusted risk of 7-day, 30-day, and 1-year mortality for patients with recurrent AMI treated with thrombolysis in comparison to patients without thrombolysis was OR 1.69 (1.07-2.65), 1.52 (1.03-2.23), and HR 1.18 (0.90-1.55), respectively. The mortality rate among patients treated with early percutaneous transluminal coronary angioplasty/coronary artery bypass grafting was 3% versus 12% at 7 days (OR 0.36 [0.16-0.73]), 7% versus 18% at 30 days (OR 0.45 [0.25-0.77]), and 16% versus 29% at 1 year (HR 0.64 [0.46-0.96]), in comparison to patients without revascularization.

CONCLUSION

The prognosis of patients with recurrent AMI improved significantly during the reperfusion era. Although thrombolysis may have a limited therapeutic effect among patients with recurrent AMI, an interventional approach seems more appropriate when indicated. A randomized trial of thrombolysis versus early revascularization is needed in patients with recurrent AMI.

Achieving tissue-level perfusion in the setting of acute myocardial infarction

Treatment for ST-elevation myocardial infarction (MI) has advanced rapidly in the last few years with improvements in early fibrinolytic therapy, primary percutaneous revascularization, and use of potent platelet glycoprotein IIb/IIIa inhibitors. It is now obvious that establishing epicardial patency after myocardial infarction is not synonymous with tissue-level perfusion. Techniques and therapies are now available that measure true tissue-level perfusion and that may improve tissue-level perfusion after myocardial infarction.

Corrected TIMI frame count does not predict 30-day adverse outcomes after reperfusion therapy for acute myocardial infarction

BACKGROUND

Thrombolysis in Myocardial Infarction (TIMI) flow grading is limited by subjectivity and imprecision. The corrected TIMI frame count (cTFC) has been proposed to obviate these problems. We sought to validate the utility of the cTFC in predicting adverse clinical outcomes after reperfusion therapy.

METHODS AND RESULTS

We used angiographic core laboratory data from the Intravenous nPA for Treating Infarcting Myocardium Early Study (lanoteplase versus alteplase) to assess the predictive capacity of both final TIMI flow and cTFC on 30 day-composite adverse outcome (death, reinfarction, and new or worsening congestive heart failure). Only 390 angiograms of 586 were analyzable for cTFC; 33.4% of angiograms could not be analyzed for cTFC because filling of distal landmarks was not visualized for technical reasons such as inadequate panning. The interobserver correlation for determination of the cTFC was 0.99 and the intraobserver correlation was 0.97. The cTFC in the group with adverse outcomes was 49 +/- 34; in the group without adverse outcomes, it was 44 +/- 31 (P =.27). Of note, the TIMI flow correlated with adverse outcome in the overall group of patients (P =.018, area under the receiver-operator characteristic curve [c] = 0. 590) as well as in the group of patients with cines analyzable for cTFC (P =.025, c = 0.600). The independent correlates of adverse outcomes were age (P <.001), heart rate (P =.001), TIMI flow grade (P =.027), and infarct location (P =.038) but not cTFC.

CONCLUSIONS

The cTFC did not predict adverse outcomes in this population of patients but did show excellent reproducibility within our core laboratory.

Coronary artery flow ten weeks after myocardial infarction or unstable angina: effects of combined warfarin and aspirin therapy

Forty-three patients presenting with unstable angina or myocardial infarction were randomised double blind to warfarin [target international normalised ratio (INR), 2.0 to 2.5] and aspirin (150 mg) daily or placebo plus aspirin (150 mg) daily. Coronary flow was assessed with the thrombolysis in myocardial infarction (TIMI) flow grade and corrected TIMI frame count (CTFC). Coronary artery flow was reduced (higher CTFC) at baseline in culprit arteries (mean +/-SD, 37.1+/-15.4 frames) compared to nonculprit arteries (22.5+/-6.7 frames, P<0.0001). In patients with a patent artery at follow-up, coronary flow was unchanged after ten weeks of warfarin and aspirin (-2.0+/-19.9 frames) or aspirin alone (3.8+/-10.4 frames, P = 0.20). Patients randomised to aspirin alone were more likely to progress to total occlusion [aspirin, 7 of 19 (37%) vs. warfarin and aspirin, 1 of 24 (4%); P = 0.01). Higher baseline culprit artery CTFC was also associated with an increased risk of late occlusion [+10 frames; odds ratio (OR), 1.65; 95% CI, 1.01 to 2.33]. Coronary flow remained impaired ten weeks after presentation with myocardial infarction or unstable angina. Combination warfarin and aspirin therapy did not improve flow in vessels that remained patent but did reduce the risk of progression to occlusion.

Long-term arterial patency after coronary reperfusion

Coronary reocclusion is a frequent event after reperfusion and may be responsible for the deterioration of left ventricular function. It may occur early as well as in the chronic phase after hospital discharge. Current, evidence based, strategies to prevent reocclusion include antiplatelet and anticoagulant agents as well as the use of intracoronary stenting in those patients who are treated by PTCA. The combination of aspirin and ticlopidine adds on the results of stenting. Further treatments are currently investigated and may significantly improve the long-term coronary patency.

Complex stenosis morphology predicts late reocclusion during follow-up after myocardial infarction in patients with patent infarct-related coronary arteries

BACKGROUND

Whether angiographic morphology of infarct-related residual stenoses continues to affect prognosis after discharge is not known.

METHODS

We studied 175 patients after their myocardial infarction who required nonurgent coronary angioplasty for residual myocardial ischemia. The findings at diagnostic coronary angiography were compared with those before angioplasty (mean of 7 months later). Infarct-related stenoses were classified as complex or smooth. Stenosis progression was defined as >0.5 mm diameter reduction.

RESULTS

One hundred twenty-one (69%) infarct-related stenoses were complex. At restudy, total occlusion was found in 41 (35%) of the infarct-related complex stenoses compared with 7 (13%) smooth stenoses (P = .001). Reocclusion occurred in 16 (55%) of 29 complex infarct-related stenoses with thrombus, compared with 25 (28%) of 88 without thrombus (P = .01). During follow-up, 46 patients (26%) had cardiac events. Of these, 70% had complex lesions at study entry compared with 30% smooth (P < .05).

CONCLUSIONS

Residual angiographically complex stenoses after an uncomplicated myocardial infarction are associated with a greater risk of reocclusion and may predispose to coronary events at follow-up.

Incidence and predictors of restenosis after successful primary coronary angioplasty for acute myocardial infarction: the importance of age and procedural result

BACKGROUND

Previous studies have suggested that restenosis and reocclusion occur frequently in patients with acute coronary syndromes. This study was undertaken to assess the incidence and predictors of restenosis in a cohort of patients who underwent successful primary coronary angioplasty for acute myocardial infarction.

METHODS

Three hundred twelve patients who underwent successful primary angioplasty of a native coronary vessel were candidates for follow-up coronary angiography. This was performed in 284 patients (92%) at the 3- or 6-month follow-up. Quantitative coronary angiography was performed with the CMS system. Multivariate analysis was performed to determine independent predictors of restenosis.

RESULTS

Restenosis, defined as a diameter stenosis of >50%, occurred in 27% of patients at 3 months and in 37% of patients at 6-month follow-up. Reocclusion occurred in 4% and 6%, respectively. Reference diameter (vessel size) was related to restenosis. Age and lumen diameter immediately after angioplasty were independent predictors of restenosis. Young patients (<50 years) and patients with a minimal luminal diameter of more than 2.5 mm had restenosis rates of <25%. The radionuclide ejection fraction was 46% in patients with restenosis compared with 47% in patients without restenosis.

CONCLUSIONS

The incidence of restenosis after successful primary coronary angioplasty for acute myocardial infarction is comparable to the reported incidence after elective coronary angioplasty for stable angina. Restenosis is related to age and the lumen diameter after angioplasty and does not affect left ventricular function in this population.

The Open Artery Hypothesis: Past, Present, and Future

The survival benefit following a reperfusion strategy, be it pharmacologic or mechanical, appears to be due to both full and early reperfusion. While the TIMI Flow Grade classification scheme has been a useful tool to assess coronary blood flow in acute syndromes, it has several limitations. A newer method of assessing coronary blood flow called the Corrected TIMI Frame Count method has the following advantages: (1) it is a continuous quantitative variable rather than a categorical qualitative variable; (2) the flow in the non-culprit artery is not assumed to be normal as it is in the assessment of TIMI Grade 3 Flow; (3) there is simplified reporting of reperfusion efficacy through the use of a single number instead of expressing the data in 2 to 4 categories; (4) because a single number rather than 4 categories is used to report the data, there is more efficient use of the dataset by increasing the statistical power; and finally (5) coronary flow can be expressed in intuitive terms (e.g. time or cm/sec for strategy A versus time or cm/sec for strategy B). This paper reviews the history of the open artery hypothesis and recent advances in the field.

Regional expansion during myocardial ischemia predicts ventricular fibrillation and coronary reocclusion

Primary ventricular fibrillation (VF) complicating acute myocardial infarction is associated with occluded infarction-related arteries. The relationship between VF during ischemia and spontaneous coronary reocclusion was analyzed in 48 anesthetized pigs submitted to 48 min of coronary ligation and 6 h of reflow. Reocclusion was associated with ischemic VF (6 of 11 animals with VF but only 6 of 37 without it had reocclusion) but not with reperfusion arrhythmias, the size of the ischemic area, the magnitude of electrocardiogram changes or contractile dysfunction during ischemia, or the severity of intimal injury at the occlusion site. The increase in end-diastolic length in the ischemic region during coronary occlusion was associated with ischemic VF (15 min after occlusion, end-diastolic length was 116 +/- 2 and 111 +/- 1% of baseline in animals with or without presenting subsequent VF, respectively) and was retained by multiple logistic regression analysis as the only independent predictor of ischemic VF and reocclusion. Thus ischemic VF is strongly associated with an increased rate of spontaneous coronary reocclusion during subsequent reperfusion. Acute expansion of ischemic myocardium appears as a prominent determinant of both ischemic VF and reocclusion.

Abnormal coronary flow in infarct arteries 1 year after myocardial infarction is predicted at 4 weeks by corrected Thrombolysis in Myocardial Infarction (TIMI) frame count and stenosis severity

Because 24% to 30% of patent infarct-related arteries occlude in the year following thrombolytic therapy for acute myocardial infarction, angiographic factors including corrected Thrombolysis in Myocardial Infarction (TIMI) frame count which may predict abnormal infarct-artery flow, require definition. We examined changes in coronary flow and infarct-artery lesion severity by computerized quantitative angiography over 1 year in 154 patients with a patent infarct-related artery 4 weeks after myocardial infarction. These patients were randomized to receive either ongoing daily therapy of 50 mg aspirin and 400 mg dipyridamole, or placebo. All angiograms were interpreted blind in our core angiographic laboratory. Infarct-artery flow, assessed by corrected TIMI frame counts, was normal (< or = 27) in 46% and 45% of patients at 4 weeks and 1 year, respectively. At 4 weeks, patients with corrected TIMI frame counts < or = 27 had higher ejection fractions (60+/-11% vs 56+/-12%; p = 0.04) than those with corrected TIMI frame counts >27. On multivariate analysis, corrected TIMI frame count and stenosis severity were predictive of late abnormal infarct-artery flow (TIMI 0 to 2 flow, both p <0.01). Only stenosis severity at 4 weeks predicted reocclusion at 1 year (p <0.0001). Aspirin and dipyridamole had no effect on flow or reocclusion. Thus, corrected TIMI frame count and stenosis severity at 4 weeks was highly correlated with infarct-artery flow at 1 year.

Prognostic significance of spontaneous echo contrast in the thoracic aorta: relation with accelerated clinical progression of coronary artery disease

OBJECTIVES

The purposes of this study were to identify the incidence of aortic smoke in an unselected cohort of patients and to determine the utility of this measurement as a clinical marker for future coronary events and long-term cardiac prognosis.

BACKGROUND

Although spontaneous echo contrast detected within the cardiac chambers has been associated with an increased risk of thromboembolism, less is known about "smoke" within the thoracic aorta and its relation to progression of coronary artery disease.

METHODS

We prospectively assessed 118 unselected, consecutive male patients (mean age 67 years, range 29 to 86) who underwent transesophageal echocardiography (TEE). The presence of aortic smoke was identified by swirling echodense shadows distinct from high gain artifact. A positive result required confirmation by two of three independent observers.

RESULTS

Aortic smoke without dissection was found in 25 of the patients (21%). Indications for TEE, coronary risk factors, the incidence of reduced left ventricular ejection fraction and mitral insufficiency and known coronary artery disease severity collectively did not differ significantly at baseline between the groups with and without smoke. Follow-up averaged 20.4 months (range 18 to 24) and was 100% complete for mortality and 98% complete for morbidity. The presence of aortic smoke was an independent predictor of myocardial infarction (16.0% vs. 2.2%, p < 0.005) and cardiac death (20.0% vs. 1.1%, p < 0.0001). These statistics remained significant after covarying for age, ejection fraction < 50%, hypertension, diabetes, aortic dimension, the presence of an atheromatous plaque and smoke in the left atrium.

CONCLUSIONS

Spontaneous echo contrast detected within the thoracic aorta by transesophageal echocardiography is a common and important clinical marker that is strongly associated with an increased risk for future myocardial infarction and cardiac mortality. Future studies will attempt to define the pathophysiology of this relation and assess whether aggressive revascularization strategies and antithrombotic therapy may aid in the reduction of this risk.

Significance of the Thrombolysis in Myocardial Infarction scoring system in assessing infarct-related artery reperfusion and mortality rates after acute myocardial infarction

Thrombolysis in Myocardial Infarction (TIMI) flow scores were originally devised as semiquantitative angiographic measures of coronary artery perfusion. Several studies have indicated an important relation between different TIMI flow grades at 90 minutes after thrombolysis and clinical outcome. To further evaluate this relation we conducted a metaanalysis of all angiographic, postinfarction trials that studied the relation between individual 90-minute TIMI flow grades and mortality rates. In 4687 pooled patients, the mortality rate was lowest in patients with TIMI grade 3 flow (3.7%) and significantly lower than those with TIMI 2 (6.6%, p = 0.0003; odds ratio 0.55; 95% confidence interval [CI] 0.4% to 0.76%) or TIMI 0/1 flow (9.2%, p < 0.0001; odds ratio 0.38; 95% CI 0.29% to 0.5%). The mortality rate difference between TIMI grade 2 and TIMI grade 0/1 patients was also significant (p = 0.02; odds ratio 0.7; 95% CI 0.51% to 0.94%). This study confirms the importance of achieving rapid and complete reperfusion after acute myocardial infarction with the best outcome associated with 90-minute TIMI 3 flow. Furthermore, it shows that although TIMI 2 flow (partial perfusion) is not equivalent to TIMI 3 flow, it nevertheless still confers a significant survival benefit compared with TIMI flow 0/1.

Incidence and importance of thrombolysis in myocardial infarction grade 3 flow after primary percutaneous transluminal coronary angioplasty for acute myocardial infarction

We analyzed angiographic flow and myocardial salvage in 180 patients who underwent primary percutaneous transluminal coronary angioplasty (PTCA) without antecedent thrombolytic therapy for acute myocardial infarction. Thrombolysis in Myocardial Infarction (TIMI) flow grade was analyzed visually before and after PTCA. All patients underwent paired baseline (before angioplasty) and predischarge quantitative tomographic perfusion imaging with technetium-99m (Tc-99m) sestamibi techniques for assessment of the initial area at risk and final infarct size. The myocardial salvage index was defined as the proportion of jeopardized myocardium that was salvaged. After primary PTCA, TIMI grade 3 flow was obtained in 163 patients (91%), TIMI grade 2 flow in 13 patients (7%), and TIMI grade 0 or 1 flow in 4 patients (2%). There was a significant association between TIMI flow and both infarct size and salvage index. Infarct size was significantly smaller in patients with TIMI grade 3 flow than in those with TIMI grade 2 flow (15 +/- 16% vs 29 +/- 21% of left ventricular mass, p = 0.007). The salvage index was 55 +/- 41% of the area at risk in the TIMI 3 group and 27 +/- 38% of the area at risk in the TIMI 2 group (p = 0.04). After primary PTCA, restoration of TIMI grade 3 flow was necessary for optimal myocardial salvage. TIMI grade 2 flow was associated with a larger final infarct size and a lower salvage index.

Reocclusion: the flip side of coronary thrombolysis

Since the introduction of thrombolytic therapy for acute myocardial infarction, the incidence of coronary artery reocclusion has been intensively studied. Also, the prediction and diagnosis of reocclusion by angiographic and clinical variables, as well its invasive and pharmacologic prevention, have gained much attention. By angiographic definition, reocclusion requires three angiographic observations: one with an occluded artery, one with a reperfused artery and a third for the assessment of subsequent occlusion (true reocclusion). Since the introduction of early intravenous reperfusion therapy, most studies use only two angiograms: one with a patent and one with a nonpatent infarct-related artery. A search for all published reocclusion studies revealed 61 studies (6,061 patients) with at least two angiograms. The median time interval between the first angiogram after thrombolysis and the second was 16 days (range 0.1 to 365). Reocclusion was observed in 666 (11%) of 6,061 cases. Interestingly, the 28 true reocclusion studies showed an incidence of reocclusion of 16 +/- 10% (mean +/- SD), and the 33 studies with only two angiograms 10 +/- 8% (p=0.04), suggesting that proven initial occlusion of the infarct-related artery is a risk factor for reocclusion after successful thrombolysis. The other predictors for reocclusion are probably severity of residual stenosis of the infarct-related artery after thrombolysis and perhaps the flow state after lysis. Reocclusion is most frequently seen in the early weeks after thrombolysis. The clinical course in patients with reocclusion is more complicated than in those without this complication. Left ventricular contractile recovery after thrombolysis is hampered by reocclusion. Routine invasive strategies have not been proven effective against reocclusion. In the prevention of reocclusion, both antiplatelet and antithrombin strategies have been tested, including hirudin and hirulog, but the safety of these agents in thrombolysis is still questionable. Thus, reocclusion after thrombolysis is an early phenomenon and is more frequent after proven initial occlusion of the infarct-related artery. Reocclusion can be predicted by angiography after thrombolysis. Because reocclusion is detrimental, strategies to prevent it should be developed and carried out after thrombolytic therapy for acute myocardial infarction as soon as they are deemed safe.